textproduct: Albany

WHAT HAS CHANGED

No significant changes with this update. Still expecting a light snow event this morning which can lead to slippery travel mainly through midday.

KEY MESSAGES

1) Light snow expected this morning, with locally slippery travel conditions expected followed by much colder temperatures tonight through tomorrow night.

2) Increasing chances for an initial period of snow on Tuesday that changes to rain and/or a wintry mix, mainly near and south of I-90. There remains uncertainty regarding snowfall amounts and areal coverage of wintry mix.

3) Moderate confidence for temperatures to trend warmer than normal for the end of the week into this weekend, especially in valley areas, which will likely ripen and partially melt the existing snow pack. With multiple opportunities for precipitation during this period, the combination of falling rain plus melting snow may start to break-up existing river ice.

DISCUSSION

KEY MESSAGE 1...

Latest water vapor imagery shows a shortwave trough tracking through western NY early this morning with sfc observations showing a cold front at the sfc beneath it with a sharp wind shift to the north behind the boundary. Weak mid-level warm air advection combined with cyclonic vorticity advection has allowed snow to develop along this boundary as shown in the regional radar mosaic with high res guidance continuing to show a period of snow expanding into areas along and west of the Hudson River by 09 - 12 UTC this morning. With temperatures in the 30s likely cooling into the 20s in response to wet-bulbing diabatic cooling processes once snow begins, slippery travel conditions can occur early this morning due to incoming period of light snow. While overall forcing is weak, forecast soundings show lift briefly overlapping with the dendritic snow growth zone so snow can turn steady for a period this morning. The boundary continues shifting eastward this morning, tracking into areas east of the Hudson River and western New England by 12 - 15 UTC before finally exiting to our east by 18 UTC, putting an end to the snow. Given the brief nature of the snow and light QPF amounts, only expecting coating to 1 inch of new snowfall across eastern NY and western New England with a 20 to 40% chance that amounts exceed 1 inch mainly south of I-90.

After snow ends early this afternoon, northerly winds turn a bit breezy ushering in a much cooler air mass into the Northeast (especially compared to the brief warm-up we had yesterday) under clearing skies. Large scale and strengthening Canadian high pressure builds into the Northeast tonight, supporting ideal radiational cooling conditions as winds gradually weaken and skies remain clear. We followed suite with the previous forecast and sided on the cooler end of the temperature guidance for overnight lows tonight with widespread single digit low temperatures likely given probabilistic guidance shows 75%+ chance for overnight lows to fall under 10 degrees. In fact, there is a 75% chance that the southern Adirondacks and southern Greens fall under -5F. Given weakening winds, we do not have concerns for dangerous wind chills overnight.

KEY MESSAGE 2...

High pressure remains in effect through Tuesday morning before sliding off the East Coast. While mainly zonal flow continues aloft, a weak shortwave from the Midwest shifts eastward, inducing warm air advection in the Northeast Tuesday into especially Tuesday night as a warm front the mid-Atlantic lifts northward. Guidance continues to show the strongest warm air and moisture advection holding off until Tuesday afternoon/night which is when we have likely and categorical POPS spreading from north to south into the region. Initial temperatures looks cold enough to support snow or rain/snow mix with the highest chance for mainly snow for areas north of I-90. Continued warm air advection into Tuesday night should support a changeover to mainly rain for areas south of I-90. There are low to medium chances for pockets of freezing rain especially in the higher terrain areas near and north of I-90 Tuesday night as warm air advection continues aloft but ground temperatures remain colder. Still uncertainty on exact coverage and duration of freezing rain but we continue to message it in the latest forecast update. Given warming temperatures overnight, impacts from any freezing rain should be limited to slippery travel conditions. Otherwise, the zonal flow should allow limit warming for areas north of I-90 supporting mainly snow as the precipitation type into Tuesday night. Latest 24hr snowfall probabilistic guidance shows only a 10 to 30% chance for snowfall amounts to exceed 4 inches by 7AM Wednesday north of I-90. Thus, impacts again should be limited to mainly slippery travel which generally matches with the probabilistic WSSI for minor impacts through 7AM Wed.

KEY MESSAGE 3...

Heading into the end of this week into next weekend, there is increasing confidence for temperatures to trend above normal with multiple opportunities for precipitation given multiple shortwaves and boundaries. In fact, there is a 35 to 65% chance for precip amounts to exceed 0.75" over the 72 hr window ending 7AM Sunday. With the increasing temperatures, mainly rain is favored as the precipitation type with less confidence in higher terrain areas which could struggle to warm at times, favoring more snow or wintry mix. The latest probabilistic guidance from the NBM shows greater than 75% chance for high temperatures to exceed 40 degrees each day Wednesday through Saturday in valley areas across eastern NY and western New England with the highest probabilities on Saturday. Local research shows that river ice at least 1 foot thick plus daily average temperatures at or above 42 degrees and an increase in river flow typically increases the potential for break-up jams on rives. Therefore, we will be closely monitoring temperature trends to learn how much of the existing snow pack can ripen/melt. Less confident in temperatures rising above normal in the higher terrain areas of the southern Adirondacks and southern Greens where 20 to 30 inches of snow is still on the ground. Even if warming is limited to the valley areas, the combination of incoming rain and snow melt could provide the necessary mechanisms to at least start breaking up existing ice on rivers. We will continue to closely monitor temperature and precipitation trends for the end of this week into this weekend.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

Through 06z Monday...VFR conditions currently prevail across all terminals early this morning with clouds gradually overspreading the region from northwest to southeast in advance of a weak upper-level disturbance. The KENX radar shows to weak returns associated with these clouds, but according to latest observations, nothing is reaching the ground just yet. Latest guidance does indicate, however, this initial broken line of showers becoming more spatially consistent and tracking through the terminals later this morning. Based on some low-level dry air indicated on forecast soundings and overall weak forcing with this system it is uncertain just how the terminals will be impacted by these snow showers. While each looks to experience a brief period of showers, there is potential for rates to remain very light and not drop conditions into the IFR category. Based on this uncertainty, we kept snow showers in PROB30 groups with MVFR conditions, with both visibility and ceiling height, between 10-15z. Once these showers have concluded, a gradual improvement in ceiling height will see conditions return to VFR by this afternoon/this evening for all terminals. Winds throughout the period will prevail out of the north, but vary out of the northeast and northwest. Sustained speeds overnight will primarily fall below 10 kt, but a developing breeze this afternoon will see sustained speeds increase to 10-12kt with gusts of 15-25kt particularly at KALB/KPSF/KPOU.

Outlook...

Monday Night: No Operational Impact. NO SIG WX. Tuesday: High Operational Impact. Likely RA...SN. Tuesday Night: High Operational Impact. Definite RA...SN. Wednesday: Low Operational Impact. Slight Chance of RA. Wednesday Night: Moderate Operational Impact. Chance of RA. Thursday: Moderate Operational Impact. Chance of RA. Thursday Night: High Operational Impact. Likely RA. Friday: Moderate Operational Impact. Likely RA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.